I would like this to be a community wiki question.
When setting up a new Salesforce instance for an organisation, what are the settings, fields, etc that you always change, and why do you change it? (eg The terminology is too American).
Please add in any qualifiers (eg only if the organisation is a Consulting company).
I would like to limit this to default settings and not apps that you install, as that needs to be a separate question.
Please edit the answer to add your contribution.